Ventilating system for motionpicture machines



Jan. 6, 1948. h K. BENKERT 2,434,193

VENTILATING SYSTEM FOR MOTION-PICTURE MAQHINES Filed Feb. 23; 1945 l Y 2 sheets-sheet 1 mvENToR Y- /af/ ,Bhf/Merz ATTORNEY.

Jan. 6, 1948. K. BRENKERT VENTILATING SYSTEM FOR MOTION-PICTURE MACHINES Filed Feb. 23, 1945 2 Sheets-Sheet 2 INVENTOR. A/a//fH/fef ffy. 3

ATTORNEY.

Patented Jan. 6, 1948 UNITED STATES PATENT OFFICE VENTILATING SYSTEM FOR MOTION- PICTURE MACHINES '2 Claims. 1

The present invention pertains to a novel ventilating system for a motion picture projector and has for its general object the provision of means for effectively and efciently cooling the aperture plate. This application contains subject matter disclosed in my copending Patent No. 2,378,682

of June 19, 1945.

In Patent N0. 2,194,585 Of March 26, 1940, as-

signed to the Brenkert Light Projection Company, there is shown a suction system which depends for its eiiectiveness on closing off the cooling chamber from the remainder of the film compartment in order to avoid drawing unused cure rents of air .from this remaining portion of the nlm compartment. In practice however, it is difiicult to avoid leakage of air to the suction fan. While it ,is possible to close off the cooling chamber from the forward remaining portion of the iilm compartment, this requires accurate and expensive machining and assembling in order to realize the maximum effectiveness, According-ly, oneof the more particular objects of this invention is to provide a cooling system that does not require such `complete closing ofi of the cooling chamber.

This and other objects of the invention are accomplished by positively blowing air against the aperture plate .rather than drawing air 'over it by suction. Once the air is blown 'against the plate, the path subsequently taken by the air is comparatively immaterial. In the case of suction, however, air will be drawn from all *available points, and this is the condition requiring such complete closing off of the cooling chamber in the suction system disclosed in the aforementioned patent.

Another problem in connection with efficient air cooling is to mount a sufliciently large blower conveniently on the projector head, for unless these conditions are lled, the system would not be acceptable in the industry. For example, the blower as a separate unit from vthe head or awkwardly mounted on the head would not be satisfactory. Again, the conventional dimensions of a projector head and the standard distances between various parts thereof are limitations that must be considered in mounting the blowerl on .the head.

These considerations are recognized and satisfied in the present invention by positioning the blower between the shutter and the rear wall of the head. Moreover, this position enables the rotor of the blower to be mounted directly on the shutter shaft, and a shutter blade is in fact attached directly to the rotor. Neither does the blower interfere with the use vof a double shutter, there being provided a second shutter shaft within the shaft that carries the previously mentioned shut-ter and rotor.

Another object of the invention is to provide a system of the character described so constructed that the cooling value of air passing therethrough is maintained, by avoiding any material alteration in its temperature from the temperature of the immediately surrounding atmosphere. This object is accomplished by admitting atmospheric air directly to the blower or at least through a member, such as a shutter guard, that has no appreciable effect on .the temperature. Thus, although the immediately surrounding atmosphere may be unavoidably warmed by the arc lamp, there is no additional heating of the air in the blower or its actuating means.

The invention is fully disclosed by way of example in the following description and in the accompanying drawings in which:

Figure 1 is a side elevation of .the projector on the iilm side with the door removed, certain parts being shown in sections;

Figure 2 is a fragmentary plan section;

Figure 3 is an end view approximately on the line 3 3 of Figure 1;

Figure 4 is a detailed vertical section on a plane behind that appearing in Figure 1, and

Figure 5 is a section on the line 5 5 of Figure 4.

Reference to these views will now be made by use of like characters which are employed to designate corresponding parts throughout.

The projector disclosed herein is contained, for the most part, in a housing l similar to that shown in my Patent No. 2,194,585 of March 26, 1940, assigned to Brenkert Light Projection Company. The operating `mechanism within the housing is also similar to that shown in the patent, and a detailed description thereof is not considered necessary inasmuch as the invention does not pertain directly thereto. However, whereas the patent shows a single shutter, the device disclosed herein has a double shutter as fully described in my Patent No. 2,229,237 of January 2l, 1941, also assigned to Brenkert Light Projection Company.

Within the housing I is provided the usual partition 2 extending from front to rear and dividing the housing into a film compartment 3 and a mechanism compartment 4 as shown in Figure 2. On the partition 2 is mounted the aperture plate 5 extending into the lm compartment and lying between :the intermittent sprocket 6 and the top of the housing. The film is threaded vin the usual manner, as shown in my Patent No. 2,194,585 and in operation is engaged by a gate as also shown in said patent.

To the rear side of the aperture plate or film guide 5 is attached an aperture retaining plate 6 at a hinge 1. This member retains a removable apertured member 8 inserted in the aperture 9 of the plate 5. The outer vertical edge portion of the member 6 is bent at an angle rearwardly as indicated bythe numeral I in order to carry an air and light shield II which also extends to the top of the housing I. The member Il is clamped to the portion I by means of a thumb pad I2 of Bakelite or similar material and a screw I3. The shield II engages a panel I4 held to the housing by screws I5, while the door I6 hinged to the housing at I1 carries a fin I8 nearly contacting the aperture plate when the door is closed.

As shown in Figure 2, the member 5 is right angular in shape with one side lying against the partition 2. To this side is fastened an outwardly extending frame member I9 with opposed grooves 20 receiving a slidable change-over shutter 2|. Forward of this shutter, the frame I9 carries a vertical rod 22 on which slides one edge of a fire shutter 23, the opposite edge being received in a groove 24 in the member I9.

On the rear end of the housing are mounted upper and lower horizontal rods 25 for the purpose of supporting a shutter guard 26. One end of this guard is closed by the panel I4 as shown in Figure 2. The walls of the guard are in the nature of grilles having openings 26 to admit an ample quantity of air from the immediately surrounding atmosphere.

In the mechanism compartment 4 are journailed two concentric shafts 21 and 28 as in Patent No. 2,229,237. The shaft 21 extends into the guard 26 and carries the shutter blade 29 by means of a hub 3l and a clamp 32. The hub is xed to the shaft by a screw 33.

Both sides of the shutter guard have openings 25a and 26h to provide an unobstructed converging light path to the aperture member 8 when the shutters 2l and 23 are raised in the normal running of the machine. The shutter shafts are to one side of the openings 26a and 26h and the shutter blades, running in opposite directions, intercept the openings.

Concentric with the shafts 21, 28 a blower housing 34 is fastened to the rear wall of the housing by bolts 35. rI'he housing is formed with a discharge duct S6 extending downwardly and laterally from the housing and terminating in a forwardly extending nozzle 36 directed towards the lower edge of the aperture S. Within the housing 34 is a suitable hollow rotor or impeller 31 secured on the outer shaft 28 by a screw 33. Another shutter blade 39, also within the guard 25, is fastened to the outer side of the rotor by screws 3U. The shutter is so shaped and located, as shown in Figure 3, that it clears the annular intake port 34' of the rotor, thereby permitting free access of air to the interior thereof. The inner or forward wall of the shutter guard has an opening 38 in which the housing 34 is received, so that this housing is partly contained within the shutter guard for economy of space.

A suitable exhaust port may be provided in the top of the housing at the rear side of the aperture plate 5 to discharge the current of air that has absorbed the heat from the aperture plate and associated parts. In the construction shown an opening 39 is formed in the partition 3 adjacent to the upper end of the aperture plate, and behind this opening is mounted an impeller or rotor 40 in the mechanism chamber 4. The impeller rotates in a suitable shroud 4I discharging through an opening 42 in the top of the housing. Air is supplied to the impeller from the immediately surrounding atmosphere, enters rst at the openings 26' and flows to the intake port 34 of the rotor. In following this course, the air undergoes no appreciable change in temperature, and its original cooling capacity, at the time of entrance, is maintained within the blower system.

The portion of the lm compartment rearward of the plate 5 may be designated as the cooling chamber. The plate 5, extending substantially to the top of the housing I, in conjunction with the shield II of the same extent and engaging the lateral wall or panel I4, prevents dissipation of the air current into the forward portion of the lm compartment. The n I8 contributes to the same result either in conjunction with or as an alternative to the shield II. When the shield is employed, the fin may be omitted, if desired.

As previously stated, one of the problems in connection with aperture plate cooling is the avoidance of arc disturbance. This problem is successfully met in the present construction by directing the air current forwardly as well as upwardly. Because of the provision of this current, the shutter blades can be of the flat or nonblowing type which do not disturb the arc, even without the use 0f a protective glass between the lamp housing and the shutter. Any currents that may be deiiected rearwardly from the aperture plate are eiectively broken up by this type of shutter so that they do not reach the arc in sufficient strength to disturb it. The deiiected currents are reduced considerably or virtually eliminated if the exhaust impeller 4B is employed.

Another difficulty in providing an auxiliary cooling system is to mount the fan or blower conveniently while maintaining the standard distances between the arc, shutter and aperture plate.

I This difficulty is overcome in the present instance by mounting the impeller on the shutter shaft and in close proximity to the shutter, or partially within the shutter guard. In this position the inlets to the impeller are olset laterally from the light beam, and the intake currents are therefore less likely to disturb the arc. The arc is further protected from these currents by the intervening shutter in the manner set forth above with regard to deflected currents.

A baille 43 extends from the lower edge of the aperture plate 5 to the bottom of the housing and across the entire width of the iilm compartment, thereby completing the isolation of the cooling chamber` This separation, which includes the aperture plate 5 extending to the top of the housing, reduces the re hazard by keeping the draft out of the film-containing or forward portion of the fllm compartment.

Although a specific embodiment of the invention has been illustrated and described, it will be understood that alterations in the details of construction may be made without departing from the scope of the invention as indicated by the appended claims.

What I claim is:

1. In a motion picture machine, a housing, an aperture plate therein, an impeller housing supported in spaced relation to said aperture plate, said impeller housing having spaced lateral walls substantially parallel to the plane of said aperture plate and an intervening peripheral wall, a nozzle extending from said impeller housing and directed towards said aperture plate, an impeller rotatably mounted in said impeller housing, said impeller having an air inlet on the side thereof more remote from said aperture plate, a shutter attached to the same side of said impeller and disposed externally of said impeller housing and radially outward of said air inlet, and a guard enclosing said shutter, said guard having openings therethrough in direct communication with the immediately surrounding atmosphere, said guard having a light admission port spaced from the center oi rotation of said impeller, certain of said openings being spaced substantially from said port and from said center of rotation.

2. In a motion picture machine, a housing, an aperture plate therein, an impeller housing supported in spaced relation to said aperture plate, said impeller housing having spaced lateral walls substantially parallel to the plane of said aperture plate and an intervening peripheral wall, a nozzle extending from said impeller housing and directed towards said aperture plate, an impeller rotatably mounted in said impeller housing and having blades disposed entirely Within said impeller housing, said impeller housing that is more remote from said aperture plate, said impeller having an air inlet on the side thereof more remote from said aperture plate, a disk shutter attached to the same side of said impeller, and disposed externally of said impeller housing and radially outward of said air inlet, and a guard enclosing said shutter, said guard having open ings therethrough in direct communication with the immediately surrounding atmosphere, said guard having a light admission port spaced from the center of rotation of said impeller, certain of said openings being spaced substantially from said port and from said center of rotation.

KARL BRENKERT.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS 

